1. Field of the Invention
This invention relates generally to intramedullary devices and, more particularly, to an instrument for targeting blocking screws relative to an intramedullary device.
2. Related Art
Blocking screws are often used to supplement the installation of an intramedullary nail. There are three primary reasons for the use of blocking screws. First, blocking screws may be used to direct the path of an intramedullary nail. The nailing of metaphyseal fractures with short proximal or distal fractures is often associated with an increase in frontal and sagittal plane malalignment. As an example, the malalignment may be a result of an incorrect entry site. The blocking screw can be used to direct the path of the nail to correct this type of malalignment.
Second, blocking screws may be used to stabilize an intramedullary nail. Instability may be caused by the difference in size between the implant and the medullary cavity. If the difference is significant, the intramedullary nail will not contact the metaphyseal cortex and will translate along the interlocking screws. The blocking screws can be placed in strategic locations to functionally decrease the width of the metaphyseal medullar cavity and prevent the nail from migrating.
Third, blocking screws may be used to correct a deformity. In other words, the blocking screws are placed in the metaphyseal region in such a way as to direct the path of the intramedullary nail to correct the bone deformity.
Presently, a surgeon uses a free-hand technique or a metal jig for the insertion of blocking screws. The free-hand technique is prone to errors as the surgeon does not have an effective guide for the placement of the blocking screw. The metal jig is also undesirable because it does not allow the surgeon to verify the location of the blocking screw prior to insertion. The metal jig interferes with X-rays and image enhancers, thereby preventing verification of the blocking screw placement prior to installation.
Additionally, blocking screws may be used to align fracture fragments or stabilize fracture fragments. However, it is often difficult to correctly place the fragments prior to interlocking of the intramedullary nail or placement of the blocking screw. Typically a second surgeon or nurse is required to aid in positioning of the fracture fragments while the surgeon performs the procedure. Additional personnel increase the cost of the procedure and the amount of time required to perform the procedure. Moreover, due to the limited size of most operating rooms, additional personnel tend to crowd the operating room and decrease operating room efficiency.
There remains a need in the art for an instrument to guide or target the accurate placement of blocking screws. There also remains a need in the art for a radiolucent instrument that can be used to verify the placement of a blocking screw prior to insertion. Finally, there remains a need in the art for a device which aids a single surgeon in the proper alignment of fracture fragments.